One annoying thing about the 1994 XR650L that I recently purchased is that at idle speed it will "miss" about every 20 seconds. I don't know if it's just missing a single spark or more, but it only lasts a fraction of a second. However, if the idle is too low it's enough for the engine to die because of it. I haven't really noticed this behavior at higher engine speeds, and other than that it runs just fine under power. Things I've checked so far: Valve adjustments - one exhaust was a little bit tight, but all are in spec now and no change in behavior after the adjustment ECU - I swapped in a fairly new one from my other bike with no change Carburetion/Jetting - The bike is a lot happier after rejetting, but it didn't change this behavior. I've verified that there are no air leaks between the carburetor and engine. Things I expect to check soon: Spark plug - I'll just slap a new one in there to see if anything changes. Coil - I have a new one that I've never used. I could swap that and see if anything changes. I can't think of much else to check, but would welcome any suggestions.